This invention relates to filters for cigarettes and other smoking articles, and more particularly to cigarette filters having multiple components which are selectively flavored and/or have various cigarette smoke flow characteristics. The invention also relates to methods and apparatus for making the foregoing filters.
Cigarette filters having two or more concentric filter components may have certain advantages. For example, they may facilitate the production of cigarettes which satisfy several competing criteria with respect to such factors as filter efficiency, taste, firmness, smoke stream distribution, dilution, etc. Prior art techniques for producing such filters have, however, relied heavily on heat (and especially steam) to partially fuse and thereby stabilize each filter component as it is formed (see, for example, Berger U.S. Pat. Nos. 4,026,306; 4,046,063; 4,064,791; and 4,355,995, all of which are hereby incorporated by reference herein). Many desirable flavor additives are sensitive to heat and/or moisture. It is therefore difficult or impossible to add such flavorants to prior art composite filters. For example, commonly assigned, co-pending U.S. patent application Ser. No. 799,750, filed Nov. 19, 1985 (hereby incorporated by reference herein), discloses flavorant compositions (hereinafter generically referred to collectively as "PVA-flavorants", individually as "PVA-flavorant", or (where the flavor is menthol) as "PVA-menthol") which are activated to release their flavor by the addition of moisture. (The letters "PVA" are used in the foregoing terms merely to identify the referenced flavorants as being any of those disclosed in application Ser. No. 799,750, and not to imply that the referenced flavorants necessarily include polyvinylacetate, although the especially preferred PVA-flavorants do in fact include polyvinylacetate.) The intended source of activating moisture is the moisture in the tobacco smoke drawn through the filter when the cigarette is smoked. However, the steam used in making prior art composite filters also unavoidably activates previously applied PVA-flavorants to release their flavors, thereby increasing the difficulty of adding PVA-flavorants during the formation of composite filters (which is plainly an otherwise desirable time to add a flavorant to a filter).
In view of the foregoing, it is an object of this invention to provide improved composite cigarette filters.
It is another object of this invention to provide composite cigarette filters which can be more easily, successfully, and efficiently flavored, especially with PVA-flavorants.
It is yet another object of this invention to provide composite cigarette filters in which the various components have different flow characteristics and are selectively flavored to make more efficient use of the flavorant and/or to achieve various flavor objectives.
It is still another object of this invention to provide improved methods and apparatus for making composite cigarette filters, especially composite cigarette filters with the foregoing characteristics.